Stepping mechanisms



' March 1, 1966 R. J, CARHER 3,237,467

STEPPING MECHANISMS Filed Feb. 7, 1964 INVETOR F er- UT 'ar'fier'AT-roRNEY United States Patent O 3,237,467 STEPPIN'G MECHANISMS RogerJohn Cartier, Vimercate, Milan, Italy, assignor to Controis Company ofAmerica, Melrose Park, Ill., a

corporation of Delaware Filed Feb. 7, 1964, Ser. No. 343,304 Claimspriority, application France, Feb. 13, 1963,

3 Ciaims. (ci. 74-152) wheel, means for reciprocating the pawl toadvance the vratchet wheel through a step of one tooth at eachreciprocation of said reciprocatling means, and deactivating 'means fortemporarily rendering the pawl inoperative to advance the ratchet wheeldespite continued operation of the reciprocating means.

vThe ability to render the pawl inoperative to advance the ratchet wheelfinds application, for example in domestic laundry appliances or dishwashing machines having a programmed time switch incorporating aStepping mechanism. In such a case, it may be desirable to halt therotating parts of the time switch whenever the function of the machineis not time-controlled, for example whilst the wash water is beingheated to a predetermined temperature. i 'i f More particularly thepresent invention provides a Stepping mechanism comprising a ratchetwheel, an actuating pawl spring biassed toward engagement with the teethof the ratchet wheel, means for reciprocating the pawl to advance theratchet wheel through a step of one tooth at each reciprocation, apvoted lever having a projection thereon which, in the operativeposition of the lever, lies adjacent the ratchet teeth immediatelyapproaching the pawl and prevents the pawl during its backward movementfrom passing over the next adjacent one of these teeth into the nextintertooth space, spring biassing means acting on the lever to urge itin one direction, and control means responsive to conditions independentof the operation of the mechanism acting on the lever to urge it in theopposite direction, so that the projection on said lever is moved intoand/ or out of operation in dependence upon said conditions.

Two embodiments of the invention will now be particularly described, byway of example only, with reference to the accompanying drawings inwhich:

FIGURE l is a view in elevation of a Stepping mechanism showing aratchet wheel, an actuating pawl arranged to be reciprocated and toadvance the ratchet wheel during each forward movement, a locking pawlfor holding the ratchet wheel stationary during backward movement of theactuating pawl, and a mechanism for rendering the actuating pawltemporarily inoperative;

FIGURE 2 is a sectional view, along line II-II of FIGURE 1, of a heatingresistance and of a bimetallic element forming part of theabove-mentioned mechanism;

FIGURE 3 is a circuit diagram showing the connection of the heatingresistance of the bimetallic element of FIGURES 1 and 2, with athermostatic interrupter immersed in a liquid whose temperaturedetermines the functioning of the mechanism; and

rice

FIGURE 4 is an elevation of a modified embodiment of the mechanismadapted to be controlled electromagnetically.

As shown in FIGURE l, the Stepping mechanism comprises a ratchet wheel 1fixed on an axle 2 and arranged to advance stepwise in the direction ofarrow F, under the action of the forward movement of a control tooth 3aof an actuating pawl 3, the pawl being pvoted at 4 on a reciprocallymoving lever, not shown, and reciprocated by movement of the lever. Thepawl is biassed by a spring 5 to urge it into meshing engagement withthe teeth ofratchet wheel 1. The tooth 3a of the pawl is extendedtransversely parallel to the pivotal axis of the pawl for a reason whichwill be discussed below.

The ratchet wheel 1 is also engaged by a locking pawl 6 which holds itin position during backward movement of the actuating pawl and alsoassists in preventing overtravel of the ratchet wheel at the end of astep of advance movement. The looking pawl is pivoted at 7 and biassedby a spring 8 to hold a projection 6a of this pawl in engagement withthe teeth of the ratchet wheel.

The actuating pawl 3 can, under certain conditions,

be prevented temporarily from advancing the ratchet wheel by preventingthe pawl during its backward movement from engaging in the nextintertooth space of the ratchet wheel 1. This is effected by means of alever 10 pivoted at 11 for movement in a plane parallel to the plane ofthe ratchet wheel, this lever having towards its free end, a noseportion 10a of which the outer edge 10b is curved to match the curvatureof the envelope of the teeth of the ratchet wheel and depending on theposition occupied by the lever 10, lies either slightly outside theenvelope of the teeth of the ratchet wheel, of inwardly of the circledefined by the bottom of the intertooth spaces of the ratchet Wheel.

A spring 12, wrapped around the pivot axle of the lever 10, has one ofits ends in abu-tment with a stop 13, and its other end pressing againstthe lever 10. This spring maint'ains a bias on the lever 10 in a senseto ur'ge it into the position shown in the drawing, in which the edge101) is slightly outside the envelope of the ratchet teeth, therebypreventing the control tooth 3a of the actuating pawl 3 from falling,during the backward movement of the actuating pawl, in-to the intertoothspace situated immediately behind that which the pawl tooth occupied atthe end of the last advance of the actuating pawl.

The lever 10 has at its free extremity a flattened tongue 10c whichcooperates with the free end of a bimetallic element 14 whose oppositeend is fixed adjacent the pivotal axis of the lever 10, this bimetallicelement being Surrounded by a heating resistor 15.

Adjacent the middle of its length, the lever 10 has a recess with abent-out edge forming a feeler projection 10d. This projectioncooperates with a surface cam or lever stop 1a formed in the ratchetwheel 1, the surface cam having a recess or depression 1b at a point onits periphery.

The heating resistor 15 is connected in a circuit which can, forexample, be controlled by a thermostatic interrupter 16 subject to thetemperature of liquid L contained in a tank or cistern C.

In the modified embodiment shown in FIGURE 4, 'the clockwise movement ofthe lever 10, which is effective 'to render .the actuating pawl 3operative again, iS controlled, not by a birnetallic element, but by anelectromagnet 17 acting on an armature 18 provided at the end of one ofthe arm-s of a lever 19 pvoted on a fixed axis 20, the other arm ofwhich acts on a pin 21 fixed to -the lever 10. The bias imparted to thelever 10 by the lever 19 is partially opposed by a return spring 22.

The embodiments of the invention described above function in thefollowing way:

When, in the course of the rotation of the ratchet wheel 1, theprojection d of the lever 10 falls into the depression 1b of lever stopor cam 1a, the lever 10 pivots in an anti-clockwise direction, under theaction of spring 12. (The same result can be obtained in the absence ofspring 12, by suitably disposing and adjusting the bias of, thebimetallic strip 14.) When this happens, the nose portion 10a covers theteeth of the ratchet wheel, and the edge 10b of 'this por-tion 10a liesslightly outside the envelope of the teeth of the ratchet wheel, thuscovering the intertooth space into which the actuating pawl 3 wouldnormally engage at 'the end -of the next backward movement.

As mentioned above, the tooth 3a of the pawl is laterally extended, andwhen the tooth 3a has ridden up the face of the ratchet tooth with whichit is in engagement, further retreat of the pawl will cause the lateralextension of the pawl tooth 3a to slide on the edge 101i and so preventthe pawl tooth from dropping into the next intertooth spaoe. During thenext advance of the pawl 3, the extension of .tooth 3a will slide in theopposite direction -on edge 10b` and at the end of this movement, thepawl tooth 3a Will drop back into the same intertooth fspace as itoccupied at the beginning of the retreat movement so that no advance ofthe ratchet wheel will occur.

tIt is obvious that, to prevent the actuating pawl 3 forcing lever 10 topivot in a clockwise direction, and thus to discontinue the temporaryarrest of the advance of the ratchet wheel, it is limportant that spring12, or in the absencel of the spring 12 the bimetallic element 14, or inthe caseof FIGURE 4 the spring 22, should be strong enough to overcomethe bias of the pawl.

When the interruptin-g means 16 close (eg. under the effect of anincrease in the temperature of liquid L contained in tank C) currentpasses through the heating resistance 15, and the heat so producedraises the bimetallic element 14 to a temperature at which it acquires awarping force sufficient to cause the lever 10 to pivot in a- 'cloekwisedirection and thus permit the Stepping mechanism to function normallyunder the reciprocating action of the pawl 3. When the lever pivotsclockwise, projection 10d of the lever 10 is moved out of the depression1b of the lever stop or cam 1a and must slide on the crcular surface ofthe cam, so that if the interrupter 16 opens, the lever 10 is no longerfree to pivot into the position which renders the pawl 3 inoperative.

The lever 10 can be subjected to the action of control means other thanspring 12 (or 22) or zthe bimetallic element 14. For example a slidingbolt could be used to coopera'te with the lever 10, to urge it into aposition in which the pawl is rendered inoperative.

Although only two embodiments of the invention have been particularlydescribed, it will be evident to those skilled in the art that otherembodimen-ts can be construoted without departing from the scope of theinvention as defined by the claims appended hereto.

I claim:

1. The combination with a Stepping mechanism of the type having aratchet wheel engaged by a pawl adapted to be reciprocated to advancethe wheel in a step-by-step manner, -of means for rendering 'theStepping mechanism inoperative, comprisin-g, a mask movable between aninoperative position and an operative position in which it lies adjacentthe ratchet wheel and is engageable by the pawl as the pawl isreciprocated whereby the pawl cannot engage ratchet teeth to effectadvance of the ratchet wheel, a lever supporting the mask, means biasingthe lever to move the mask to its operative position, a lever stop fixedon the wheel, a portion of the lever riding on the lever stop to holdthe lever and mask in the inoperative position, said stop including adrop portion allowing the biasing means to move the lever to itsoperative position When the lever portion registers with the dropportion of the lever stop whereby the Stepping mechanism is renderedinoperative in a precise angular position of the wheel, and means formoving the lever to it-s inoperative position.

2. The combination of claim 1 in which the means for moving the lever toinoperative position comprises a bimetal and a heater therefor.

3. The combination of claim 1 in which the means for moving the lever toinoperative position comprises a solenoid.

References Cited by the Examiner UNITED STATES PATENTS 1,759,856 5/1930Klein 74-151 2,'281,`262 4/ 1942 Breitenstein 74-149`X 2,343,549 3/1944Groghan 74-150 2,797,795 7/ 1957 West. 3,059,488 10/1962 Daubenberger74-152 X BROUGHTON G. DURI-IAM, Primary Examncr.

1. THE COMBINATION WITH A STEPPING MECHANISM OF THE TYPE HAVING ARATCHET WHEEL ENGAGED BY A PAWL ADAPTED TO BE RECIPROCATED TO ADVANCETHE WHEEL IN A STEP-BY-STEP MANNER, OF MEANS FOR RENDERING THE STEPPINGMECHANISM INOPERATIVE, COMPRISING, A MASK MOVABLE BETWEEN AN INOPERATIVEPOSITION AND AN OPERATIVE POSITION IN WHICH IT LIES ADJACENT THE RATCHETWHEEL AND IS ENGAGEABLE BY THE PAWL AS THE PAWL IS RECIPROCATED WHEREBYTHE PAWL CANNOT ENGAGE RATCHET TEETH TO EFFECT ADVANCE OF THE RATCHETWHEEL A LEVER SUPPORTING THE MASK, MEANS BIASING THE LEVER TO MOVE THEMASK TO ITS OPERATIVE POSITION, A LEVER STOP FIXED ON THE WHEEL APORTION OF THE LEVER RIDING ON THE LEVER STOP TO HOLD THE LEVER AND MASKIN THE INOPERATIVE POSITION, SAID STOP INCLUDING A DROP PORTION ALLOWINGTHE BIASING MEANS TO MOVE THE LEVER TO ITS OPERATIVE POSIWHEN THE LEVERPORTION REGISTERS WITH THE DROP PORTION OF THE LEVER STOP WHEREBY THESTEPPING MECHANISM IS RENDERED INOPERATIVE IN A PRECISE ANGULAR POSITIONOF THE WHEEL, AND MEANS FOR MOVING THE LEVER TO ITS INOPERATIVEPOSITION.